Has anyone done this trip recently?
There are a couple of threads here which talk about taking the boat to China, but they're pretty scant on information and are out of date anyway.
I'm really interested in experiences, particularly the train, with regard to total price, total time taken, and anything else people remember from the trip.

Haven't done it myself, but it sounds like it could be a fun trip--of course, I'm assuming that you're doing it for the sake of the trip itself and not the much faster and cheaper option of just flying to HK.

You could ferry to Tanjin and get to Beijing, then take the Beijing to HK train. It's probably possible to buy this all in one package from a travel agent which would avoid a certain amount of hassle, but might not be as fun. Up to you.

We took a cruise ship out of Pusan to two ports in Japan and then straight into Shanghai harbour. Pretty cool. Italian liner. My sis-in-law scored the tickets last minute. Might be able to find out more on the net. Interesting exprience.